Hod Carrier

[MOC] Self-contained 4 wide loco

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Following the completion of my 4-wide Sprinter Light Train (SLT) model there was some discussion about whether or not it would be possible to power it using HO model railway components. This got the old grey matter working and had me thinking about the possibility of a powered 4-wide model. The notion of using model railway components fused with LEGO did not appeal as I wanted to use LEGO power components wherever possible.

Some long nights followed where I basically tore down the SLT in LDD to try and find out what is or is not possible. Having seen AussieJimbo's excellent 4-wide diesel I knew it must be possible, but sadly the SLT was not a good candidate for motorisation. However, I did learn some valuable lessons and arrived at the conclusion that any such model would have to be designed from the ground up as a powered model, and that it would most likely have to be a loco rather than an EMU passenger train. I also decided that I wanted the loco to be fully enclosed and self-contained so that it could run independently and would not need to rely on a tender to carry the power supply and receiver. And so I used that as a starting point, fired up LDD and settled-in for some long nights of brainstorming.

My original thoughts were to use PF components wherever possible but I immediately had to discard all the various battery boxes. Having designed the drivetrain using a single M Motor and Space2310's power bogie design from his narrow gauge Series 1000 Enoden train I set about creating enough space to accommodate a 9 volt PP3 battery. More problematic was the infra-red receiver which I could not package in such a way that it would not block the cable runs from the battery to the motor. In the end I relented and opted for the smaller SBrick.

This is the stage that I am at now. The model is intended to be of a Dutch Bombardier TRAXX electric loco, although this chassis could conceivably be used for any Bo-Bo loco.

24409119666_1329991916_z.jpg

I have translated the designs into a running prototype that is still awaiting detailing. I've been building the model in stages just in case I hit a fatal design flaw (which is also why it's been developed in secret up to this point).

24066857859_cd972f8551_z.jpg

Drive is to a single bogie only which is sufficient for it to drive itself around a short test track (video on my Flickr page for those interested to see as well as some more detailed photos of the internals), but it remains to be seen whether or not it has sufficient grunt and, more importantly, adhesion to haul any sort of train. However, the initial signs are good. There's sufficient clearance to the bodywork to permit enough bogie articulation to take LEGO narrow gauge curves, the drivetrain is nice and smooth and everything seems to fit together and work well enough so far.

I should obviously credit AussieJimbo for blazing the trail in powered 4-wide modelling and giving me the inspiration to see what could be achieved. Credit also goes to Space2310 for his excellent power bogie design. My model is evolutionary and could not have been realised without the foundations laid by others.

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It was instantly recognizable as the TRAXX locomotive. Don't forget to add Pantographs. Come to think of it, the Lego pantograph part would actually be perfect for this scale.

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Thanks, Beck. I've spent so much time concentrating on the mechanical parts that I had neglected the details, but I had not forgotten the pantographs. I'm not a great fan of the LEGO part and have a design that I am happy with at this scale. Unfortunately I cannot replicate this in LDD which is why it isn't shown in the screenshot.

I've since worked up a v1.1 chassis which will enable me to add some extra weight to the chassis which will hopefully help with traction. I have also turned my attention to improving the shape and appearance of the details still to be added. It looks nice in LDD but I do need to get onto Bricklink and get the relevant parts ordered.

23861120494_7a58460881_z.jpg

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Nice setup, and the train seems to run well. Thanks for sharing. The next is to build a nice track for it!

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Thanks Baard. I'm pleased with it so far.

I'm just awaiting the parts for the v1.1 chassis and will check to see what the power and haulage capabilities are first and then develop from there. If it performs well I will have a think about what sort of railway I can build for it. Obviously I'm slightly limited by having only straights and one radius of curve to work with and no points/switches, but luckily the Dutch railways don't have many natural obstacles to negotiate so it might be OK.

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Thanks guys. I think I'm going to have to borrow an official LEGO train from somewhere for some comparison shots to show the difference in size.

BnB: Yes that is an SBrick. There simply wasn't any realistic way to package the Power Functions IR receiver in the space available without having to make other design compromises. The SBrick is smaller and easier to package. I'm just using a cheap alkaline PP3 battery bought from the supermarket for testing purposes at present but will upgrade to rechargeable batteries if everything goes well. I'm sure the different power source will have a bearing on performance, so I may not be able to give you the answers just yet. Watch this space, as they say.

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The parts for the v1.1 chassis arrived and I have been able to add them to the prototype. After some head-scratching I found a way to include a boat weight to hopefully help with traction. The clearances are so tight that the only way it could fit is to attach it directly to the underside of the motor.

24412113590_0cd659e9a9_z.jpg

I've also added a few more of the details to the roof, but yes, the pantographs are still missing.

Traction has been improved, but only from non-existent to slight. It was able to move two SLT cars on a short straight track, but not without a lot of effort and wheelspin (video again on my Flickr page). Add any more weight or throw in a curve and it's going to slip to a stand. Some of this can be mitigated with a careful hand on the throttle, but what it really needs is more power, weight or, preferably, both and there really isn't enough space inside the model to add either, nor yet a way to transmit power to the second bogie.

It would seem that the project has come to it's conclusion, unless anyone has any suggestions. What have I missed? What other solutions might there be?

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You seem to have already put the weight brick as close to the powered bogie as possible. I assume you've tried different gearing.

Other things you could try, maybe a 9v 4x4 motor (or old 4.5v technic motor even) would have better traction even if slower, certainly would give you bit more space.

Also for space you could make or get one of Codefox's open source 2x3 bluetooth receivers which would be smaller than an Sbrick.

For the battery you might be able to get a very flat Lipo, like the one's they use for model planes/drones, which would give a bit more space also (see http://www.eurobricks.com/forum/index.php?showtopic=120326)

If all that space saving works than you might get the space required to add another 4x4 motor and power the second bogie.

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Hi B&B,

Thanks for the ideas. :o)

I'm not aware of the Codefox bluetooth receiver and can't seem to find anything quickly using the site search function. Can you help me? This might be the best option for creating space if it can fit inside one of the cabs rather than in the body of the loco. At the very least it might give me somewhere to put more ballast weight.

I had a look at the 9V motor range. While the 4x4 motors have a small footprint they are rather tall at 3 1/3 bricks. The 5x4 motor has a lower profile at 2 1/3 bricks, but it's total dimensions are barely less than the PF M motor I'm currently using. There would be no problems using one motor, but squeezing a second one in there is surely impossible.

The loco is already geared down by a fairly modest ratio of 1.5:1. If anything I was hoping that I could gear it UP a bit to give it some more speed (the first video I made shows it at full power). Although gearing the drive down further would give more traction it would make the model woefully slow.

I did initially think about using a LiPo similar to those used in RC electric flight but, having done some research, I decided that it wasn't right for me. Besides, although they can be flat and long rather than short and boxy, they're not necessarily any smaller than a household battery. Plus the PP3 battery has an appreciable mass that I was hoping would aid traction.

I'm stuck in a bit of a quandary. There is enough power there to haul a modest train if only I can eliminate the wheelspin. I think the problem can be overcome by adding more weight, but there will come a point where so much weight is added that it will sap the meagre power reserves simply trying to move it's own bulk. I did check the wheels on the SLT to make sure that they are free-running and not rubbing against anything before selecting it as a test train, but it does use small train wheels on snap axles which may not be ideal. They spin freely enough when there is no weight resting on them but maybe they bind once they are bearing the weight of a vehicle. Also the limited stock of track I possess has a serrated surface on top which presumably is meant to help give grip to the driven wheels of a loco but might actually be adding to the drag on the unpowered wheels of the train.

Thoughts...??

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You could try replacing the traction bands on your train wheels with some o-rings. I don't remember now exactly which size is usually used, but I have replaced the O-rings on one or two particularly tractionless locos and that was all I needed to do. It's certainly easier than redesigning the entire thing!

As for Codefox's receiver, you can find that right here. In a bit of coincident timing, I actually just got one installed into one my current, nearly finished locos. It is actually closer to 4x4 bricks, not counting the extra space needed for the wires, but it is only about two plates tall and is very easy to work around. I haven't put it through any serious paces yet, but it seems to be handling 2 L-motors just fine so far.

Edited by Daedalus304

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For Codefox's bluetooth receiver I think legoman666 can build some based on the released specifications if you send him a PM, I maybe doing the same thing myself very shortly for another project.

For size of motor and Lipo, maybe if you went all the way down to 4.5v motors you could also get a smaller battery.

If you don't aim to get power to the second bogie, certainly using technic wheels with bands on the unpowered bogie is going to add friction, especially with the old toothed track. Replacing the technic wheels would be ideal, but not sure how that would be possible on narrow gauge, you might be able to use 12v style wheels stuck into the older technic pins rather than a 2x4 brick but then that won't match the height of the powered bogie, certainly the best wheels friction wise are the modern non-technic type but don't know of a way of fitting those without using the wheel holder.

For straight track you could see if you could get some ME-Model straights, as they are single piece I'm guessing they could be adapted for narrow gauge by changing the sleepers.

Edited by bricks n bolts

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Hi Guys!!

Wow!! Thanks for the quick replies. :o)

I'm keen to try the simple things first and am hoping to avoid the need to redesign the layout of the internal equipment if possible. Thanks for the links to Codefox's receiver, though. I shall be keeping that in mind.

The loco wheels are on Technic axles, as per Space2310's design, and spin through 90 degree Technic cross blocks. Although they are not as good as the newer train wheel holder, I need the non-powered bogie on the loco to be of the same design so that the model is balanced. I'm sure it is a source of unwanted friction, but unfortunately there isn't really any way around that. I've already slackened off the various bushes on both bogies to make sure that the axles spin as freely as possible, and the loco has no trouble driving itself around the test track even without the added weight brick.

The concern I have is not so much with these but the wheels and axles on the test train I was using, which are the small train wheel (PN: 50254) on the snap axles of a bearing plate (PN: 4600). Again, there really isn't any way to avoid using these because of the scale of the model and the gauge of the track. I have one or two ideas that I'm going to try which I hope will reduce friction on the axles of both loco and train in the hope of improving performance and see what results that yields.

As this is my first powered model I wasn't aware that the LEGO traction tyres were such poor performers. What are people using in their place? Are we talking about the humble rubber band in an appropriate size or are there other O-rings that folk can recommend?

Thanks again for your help. :o)

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I did a narrow gauge 5w mining train a while back that had problems with traction. I never really solved it completely, but I ended up adding several ounces of solder as ballast. Not a pure solution, but it certainly helped. I also replaced the stock Lego rubber bands with some that were more tacky.

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I still have some work to do on the traction issues, but I have completed the build with all the details added. There are more photos on my Flickr page as before, but here's a little taster.

24718167591_cf9e8f6336_z.jpg

If I can overcome the traction problems I'm hoping that I can use this chassis as a basis of other locos, but at the present moment it's clothed as a TRAXX loco.

Enjoy!!

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Yup, I was having traction issues with this guy as well on Indian Jones curves:

http://www.eurobricks.com/forum/index.php?showtopic=89784&hl=

I will be assembling this onto an old gray curve modified 4 wide track layout, which should help. I was getting locomotion with Space's trucks, but was getting a lot of drag (which cause slipping) in the curves.

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Did you manage to overcome the slipping issues?

I'm interested to know more about your track system. Are you not using the narrow gauge "Indiana Jones" curves?

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He probably means the old style of tracks (12V I believe) that you needed to attach them to plates (that were used as sleepers) in the same way as the tracks we got from the City mine. But the curves were also loose pieces on plates instead of molded in one piece.

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Yup, 12V rails, the geometry does get a little weird, but you can compensate for it. Much like Alexanders puffing billy layout:

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That's an amazing set-up, but it's a little hard to see from the photos exactly what he's done with the track to compensate for the track geometry problems.

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Yup, 12V rails, the geometry does get a little weird, but you can compensate for it. Much like Alexanders puffing billy layout:

https://www.flickr.c...157655766054621

Magical layout. Love to know how that steam rake in the video was motorised. There's also the tantalising picture of half a switch point... and the turntable is simply awesome :wub:

That's an amazing set-up, but it's a little hard to see from the photos exactly what he's done with the track to compensate for the track geometry problems.

For curves I think you have to use the 12v inner rails as outer rails also and it all somehow works out..

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